1. Field of the Invention
This invention relates to an apparatus and method for placing an electronic signature unique to a group on a message transmitted from a member belonging to the group.
2. Description of the Related Art
Hitherto, to transmit an electronic mail (E-mail) for a business purposes, the address of a mailing list (ML) has been entered in a “From:” row for the transmitting E-mail. However, there was a problem that the “From:” row can be easily rewritten and thus the receiving members cannot check for validity. If each member of a job group uses a secret key corresponding to a certificate unique to the job group and affixes an electronic signature to the E-mail, the E-mail receiver can use the certificate to check for validity. However, because that all members belonging to the job group need to hold the secret key, the management of those secret keys tends to be cumbersome and the security becomes less sufficient with changes of the members according to the rotation of the employee.